Rack-tooth hardening machine



Jan. 7, 1958 c. A. PETHYBRIDGE 2;8l9,057

RACK-TOOTH HARDENING MACHINE Filed Oct. 18, 1955 FIG. 2.

United States Patent O RACK-TOOTH HARDENING MACHINE Charles A. Pethybridge, New Britain, Conn., assignor to The New Britain Machine Company, New Britain, Conn., a corporation of Connecticut Application October 18, 1955, Serial No. 541,208

Claims. (Cl. 266-4) My invention relates to a heat-treating device and in particular to an improved induction-hardening device for treating the teeth of a rack. This application covers improvements and modifications over the disclosures in Gridley Patent 2,582,929 and in my copending application Serial No. 541,209, tiled October 18, 1955.

It is an object of the invention to provide improved means for heat-treating gear teeth.

It is another object to provide a gear-heat-treating device particularly adapted to the treatment of rack teeth.

It is a specific object to provide a rack-treating attachment for a gear-tooth heat-treating machine.

Other objects and various further features of novelty and invention will become apparent or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

Fig. 1 is a plan view of a rack-tooth heat-treating device incorporating features of the invention;

Fig. 2 is a fragmentary front elevation of the arrangement of Fig. 1, as viewed from the section plane 2--2 of Fig. l;

Fig. 3 is a fragmentary right elevation of the arrangement of Fig. l;

Fig. 4 is a diagram schematically showing control elements for accomplishing an automatic sequence of operations with the device of Fig. 1; and

Fig. 5 is a fragmentary plan view illustrating a modification.

Briefly stated, my invention contemplates a heat-treating device in which the heat-treating element is fixed and in which suitable positioning means are employed for properly locating rack teeth for treatment by said element in quick and adjacent succession. The time consumed for the complete cycle of operation (i. e., time between treatment of one tooth and a corresponding treatment of the next succeeding tooth) is held to a minimum by a novel mechanism which not only secures accurate and positive placement of each tooth to be treated, but combines a tooth-indexing function with a tooth-placement function. The particular arrangement to be described lends itself as an attachment to existing forms of geartreating mechanism as disclosed in the above-identified patent application.

Referring to Figs. 1-3 of the drawings, my invention is shown in application to a heat-treating device employing a heat-treating element fxedly located with respect to a frame member 11. The frame member 11 includes elongated guide means 12 accommodating a reciprocable base 13 utilized for supporting the work 14. The basel 13 may be formed with further guide means 15 (Fig. 3) extending generally f transversely of the axis of guide means 12 and serving to accommodate a traverse slide 16 on which the work 14 is removably mounted." Inthe form shown, the base 13 happens to be of the variety useful also for heat-treatment of gears mounted on a spindle 17 carried by the base, and therefore the guide I Patented Jan. 7, 1958 means 15 is shown formed in a removable adapter plate 18, secured at 19 to the base 13.

In order properly to position successive teeth 20 of the rack 14 for treatment by the respective arms 21-22 of the element 10, I employ indexing means including an elongated rack plate 23, the rack teeth of which face away from the heat-treating element 10 and toward the axis of spindle 17. The rack 14 is shown supported on the plate 23 against stops 24 on clamping brackets 25, shown provided with wing screws 26 for manual clamping adjustment.

Indexing may be accomplished by directly actuating the rack 23 in a sequence of operations timed with the feed cycle of doubleacting feed means 28 for the slide 13. In the form shown, however, and particularly since the machine to which my rack-supporting means is applied is also primarily useful for treating gear teeth, I employ a gear 29 on spindle 17 in constant mesh with the rack 23, and I apply indexing and locating functions to the gear 29.

The indexing and locating mechanism may resemble that described in detail in my said copending application; thus, locating means 30 may comprise a double-acting cylinder for reciprocably positioning a locating element 31 between teeth of the gear 29. Indexing means may comprise a bell crank 32, pivoted at 33 on the base 13, and pivotally supporting at one end an indexing pawl 34 in engagement with teeth of the gear 29. A spring 35 normally urges crank 32 against a stop 36, and indexing is accomplished on the urging of the stem 37 of a hydraulic cylinder 38, driving bell crank 32 counterclockwise, in the sense of the drawing.

The remainder of the device may include a quenching head 40 immediately adjacent the heat-treating element 10, and limit switches 41--42 may be actuated by slide 13 at the forward and retracted limits of its reciprocating cycle.

The operation of my device will be better understood from the description of a cycle of operations. Referring particularly to Fig. 4, a cycle may commence upon closure of switch means 50, with the slide 13 in the fully retracted position. This operation is effective to energize solenoid 51 and thus actuate the hydraulic-control valve 52 to supply pressure lluid in the line 53, and at the same time to connect the line 54 to exhaust at 55. The line 53 is connected to the head end of the feed cylinder 28, and thus slide or base 13 is immediately advanced to position the tooth 20 in heat-treating relation with the means 10 `40. At the same time, since line 53 is also connected to the locating cylinder 30, the locating element 31 thereof is thrust into engagement with the gear 29 to hold the slide 16 throughout the heating cycle.

When the slide 13 achieves its full-feed position, switch 42 is actuated, and a timer 56 begins to determine a heat-treating interval, as adjusted by means 57, the adjustment being appropriate to the rack material and tooth hardness desired. During this interval, the supply transformer 58 for the heat-treating element 10 is energized by relay and power-control means 59-60 i Upon ,completionV of the timing interval appropriate to the particular treatment to be applied to the tooth 20, timer 56 closes a circuit to a solenoid 61 for the quench Valve 62, determining admission of quench fluid to the head 40. Power to the transformer 58 is shut 0H, and a solenoid 63 is energized to shift the control valve 52. In this shifted position, pressure liuid is suppiied to line 54, and line 53 is connected to the exhaust 5S. With these connections, both the locating means 31 and the feed means'28 are retracted, and indexing pressure is applied to the cylinder 38 for automatically indexing one tooth of the gear 29 and thus of the rack 14; the cycle thereupon repeats automatically because full retraction of slide 13 is accompanied by closure of limit switch 41 to reenergize solenoid S1. Reference may be had to my said copending application for a detailed description of the coordinated functioning of indexing and 'locating means 30-38.

In order that the machine may recycle only to the extent necessary to process the number of teeth on the particular rack being heat treated, I show counter means 65, including provision for selective manual adjustment at 66 of the number of cycles, meaning number of teeth to be treated. It will be understood that the counter may respond to operation of the timer 56 to index one count for each .timer cycle and that the counter 65 may effectively disable relay 59 or otherwise determine cessation of the recycling individual tooth-treatment process, as for example by opening the switch 50 (by means not shown).

In Fig. 5, I show a modification in which the described mechanism may be more universally applicable to the heat-treating of racks having various pitch distances between successive teeth. The indexing and locating mechanism 31-34 may be as previously described and operative on a gear 29 mounted on the spindle 17'. However, the gear 29 is in constant mesh with the rack 23 only through intermediate change-gear means involving a pivoted idler 70 and a third gear 71. The pivot 72 for the gear 71 is shown adjustably securable by means 73-74, depending upon the relative diameters and the separation of gears 29-71. It will be understood that the proportion of the number of teeth in gear 29 compared with the number of teeth in gear 71 may retiect the relation between the number of teeth per unit length in the rack 23 as compared with the number of teeth per unit length in the rack 14 being heat treated. The adjustment at '7S-74 for gear 71 will permit use of variously sized gears 71, depending upon the desired indexing displacement (i. e., tooth separation) of rack 14.

It will be appreciated that I have described basically simple mechanism for the automatic heat-treatment of rack teeth. With my mechanism, utmost utilization may be made of the machine for purely heating purposes, and the time between heat pulses is minimized. The mechanism lends itself furthermore to adaptationv to existing gear heat-treating machines and involves relatively small modication.

While I have described the invention in detail for the preferred forms shown, it will be understood that modications may be made within the scope of the invention as described in the claims which follow.

Iclaim:

1. Rack heat-treating means, comprising a frame including elongated guide means, a heat-treating element xedly mounted on said frame in general alignment with said guide means, a base slidably guided by said guide means, feed means for reciprocating said base along said guide means, toward and away from said heat-treating element, a traverse slide including work-supporting means and guided in further guide means on said base and extending generally transverse to said first-mentioned guide means, said slide including a rack elongated along the axis of said further guide means, a gear revolubly carried by said base in constant mesh with said rack, slidelocating means including a reciprocable tooth engaging element for holding an indexed position of said gear and therefore a transverse position of said rack, indexing means including actuating means coordinated with the cycle of operation of said feed means and of said locating means for indexing said gear and therefore said slide by one rack tooth for each withdrawal of said loeating means.

2. Rack heat-treating means, comprising a frame including elongated guide means, a base slidably guided 4 by said guide means, feed means for reciprocating said base along said guide means, a traverse slide including work-supporting means and guided in further guide means on. said base generally transverse to said first guide means, said slide including a rack elongated along the axis of said further guide means, a gear revolubly carried by said base and in constant mesh with said rack, slidelocating means including a reciprocable tooth-engaging element for holding a transverse position of said rack, indexing means including actuating means coordinated with the cycle of operation of said feed means and of said locating means for indexing said slide by one rack tooth for each withdrawal of said locating means.

3. In a rack heat-treating device, a frame, a tooth heattreating element mounted on said frame, said frame including elongated guide means directed toward said heattreating element, a base guided by said guide means, feed means for reciprocating said base in said guide means, an elongated rack-supporting slide guided for transverse movement on said base and including means for removably supporting a rack with the teeth thereof facing said heat-treating element, indexing and locating means for said slide for positioning successive teeth to be heat treated by said element, said indexing and locating means including an elongated index rack on said racksupporting slide and parallel to the axis of movement of said slide, a gear rotatably mounted on said base and in constant mesh with said index rack, automatic means for initiating the heating cycle for said element upon feed of a rack tooth to said element, timer means determining a period of heat treatment, automatic means for retracting said base and therefore the treated rack out of heating relation with said element upon determination of a preselected interval by said timer, and means for indexing andl locating said gear during a reciprocation of said base and slide on said frame.

4. A device according to claim 3, in which automatic means responsive to retraction of said base is effective to automatically feed `said base for repetition of the cycle of operation. v

5. In a heat-treating device of the character indicated, a work-supporting base, a heat-treating element and frame means supporting the same, guide means coacting between said base and frame means, and feed means for longitudinally `feeding said base and said frame means relatively to each other on said guide means, a traverse slide guided on said base in a direction generally transverse to the axis of feed movement, said slide means including an elongated rack, an index gear pivoted on said base and out of engagement with said rack, change gears pivoted on said base and including one gear in constant mesh with said rack and one gear in constant mesh with said index gear, index means for said index gear and therefore in driving relation with said rack for indexing said slide means in a program synchronized with the cycle of said feed means, and means for removably supporting a rack to be heat treated on said slide means, whereby for the same index gear various indexing displacements of said rack may be obtained, depending upon the setup of said change gears..

References Cited in the le of this patent UNITED STATES PATENTS 2,348,281 Brady May 9, 1944 2,521,699 Denneen et al Sept. l2, 1950 2,524,044 Denneen et al. Oct. 3, 1950 2,582,929 I Gridley Ian. 15, 1952 2,657,440 Myers Nov. 3, 1953 FOREIGN PATENTS 630,844 Germany I-une 6, 1936 

